An ion chromatographic method with a valve switching facility was developed to determine trace nitrate concentrations in seawater using two pumps, two different suppressors, and two columns. A carbohydrate membrane de...An ion chromatographic method with a valve switching facility was developed to determine trace nitrate concentrations in seawater using two pumps, two different suppressors, and two columns. A carbohydrate membrane desalter was used to reduce the high concentrations of sodium salts in samples. In this method, trace nitrate was eluted from the concentrator column to the analytical columns, while the matrix fl owed to waste. Neither chemical pre-treatment nor sample dilution was required. In the optimized separation conditions, the method showed good linearity( R >0.99) in the 0.05 and 50 mg/L concentration range, and satisfactory repeatability(RSD<5%, n =6). The limit of detection for nitrate was 0.02 mg/L. Results showed that the valve switching system was suitable and practical for the determination of trace nitrate in seawater.展开更多
The solenoid switching valve(SSV)is the key control component of heavy equipment such as continuous casting machines.However,the incompatibility of structural parameters increases the opening and closing time of the S...The solenoid switching valve(SSV)is the key control component of heavy equipment such as continuous casting machines.However,the incompatibility of structural parameters increases the opening and closing time of the SSV.Therefore,this study proposes an optimized design method for an SSV to improve its dynamic performance.First,a multi-physics field-coupling model of the SSV is built,and the effects of different structural parameters on the electromagnetic characteristics are analyzed.After identifying the key influencing parameters,second-order response surface models are established to efficiently predict the opening and closing time.Subsequently,based on the nondominated sorting genetic algorithmⅡ(NSGA-Ⅱ),multi-objective optimization is applied to obtain the Pareto optimal solution of the structural parameters under the double-voltage driving strategy.The structure of the solenoid and valve as well as the dynamic characteristics of the valve are improved.Compared with those before optimization,the optimization results show that the opening and closing time of the optimized SSV are reduced by 24.38%and 51.8%,respectively,and the volume is reduced by 19.7%.The research results and the influence of the solenoid structural parameters on the electromagnetic force provide significant guidance for the design of this type of valve.展开更多
Previous studies on droplet generation in microfluidics mainly focus on the monodisperse droplet,but limited attention has paid to the generation of droplet groups composed of multiple droplets with different volumes ...Previous studies on droplet generation in microfluidics mainly focus on the monodisperse droplet,but limited attention has paid to the generation of droplet groups composed of multiple droplets with different volumes or components.In this study,a programmable electromagnetic valve is externally connected with the microfluidic chip featuring a conventional flow-focused structure.Different from the previous situation where only one droplet is generated by a single actuation of the electromagnetic valve,by precisely controlling the opening and closing of the valve,the continuous phase fluid exhibits periodic flow in the channel,and we realized the generation of a droplet group by a single actuation of the valve,and the number and volume of the droplets in each group can be regulated.Specifically,the number of large droplets in a droplet group is mainly determined by the opening time of the electromagnetic valve and the two-phase flow rate,and the number of small droplets is dominated by the valve closing time.The volume of individual droplets in a droplet group is largely dependent on the flow rate of the continuous phase.Our study extends the understanding of microfluidic droplet formation.It provides a feasible method for the efficient preparation of polydisperse droplets,which is important for microfluidic chip-based droplet control and has potential applications in industries related to microfluidic droplets.展开更多
Pneumatic muscles with similar characteristics to biological muscles have been widely used in robots, and thus are promising drivers for frog inspired robots. How- ever, the application and nonlinearity of the pneumat...Pneumatic muscles with similar characteristics to biological muscles have been widely used in robots, and thus are promising drivers for frog inspired robots. How- ever, the application and nonlinearity of the pneumatic system limit the advance. On the basis of the swimming mechanism of the frog, a frog-inspired robot based on pneumatic muscles is developed. To realize the indepen- dent tasks by the robot, a pneumatic system with internal chambers, micro air pump, and valves is implemented. The micro pump is used to maintain the pressure difference between the source and exhaust chambers. The pneumatic muscles are controlled by high-speed switch valves which can reduce the robot cost, volume, and mass. A dynamic model of the pneumatic system is established for the sim- ulation to estimate the system, including the chamber, muscle, and pneumatic circuit models. The robot design is verified by the robot swimming experiments and the dynamic model is verified through the experiments and simulations of the pneumatic system. The simulation results are compared to analyze the functions of the source pressure, internal volume of the muscle, and circuit flow rate which is proved the main factor that limits the response of muscle pressure. The proposed research provides the application of the pneumatic muscles in the frog inspired robot and the pneumatic model to study muscle controller.展开更多
This paper reviews recent developments in digital switched hydraulics particularly the switched inertance hydraulic systems （SIHSs）. The performance of SIHSs is presented in brief with a discussion of several possib...This paper reviews recent developments in digital switched hydraulics particularly the switched inertance hydraulic systems （SIHSs）. The performance of SIHSs is presented in brief with a discussion of several possible configurations and control strategies. The soft switching technology and high-speed switching valve design techniques are discussed. Challenges and recommendations are given based on the current research achievements.展开更多
基金Supported by the National Special Fund for Major Research Instrumentation Development(No.2012YQ090229)the Instrument Functional Exploitation and Technical Innovation Fund,Chinese Academy of Sciences(No.yg2010072)the Shandong Provincial Technology Development Plan Fund(Nos.2011SJGZ06,2012SJGZ12,2012424012)
文摘An ion chromatographic method with a valve switching facility was developed to determine trace nitrate concentrations in seawater using two pumps, two different suppressors, and two columns. A carbohydrate membrane desalter was used to reduce the high concentrations of sodium salts in samples. In this method, trace nitrate was eluted from the concentrator column to the analytical columns, while the matrix fl owed to waste. Neither chemical pre-treatment nor sample dilution was required. In the optimized separation conditions, the method showed good linearity( R >0.99) in the 0.05 and 50 mg/L concentration range, and satisfactory repeatability(RSD<5%, n =6). The limit of detection for nitrate was 0.02 mg/L. Results showed that the valve switching system was suitable and practical for the determination of trace nitrate in seawater.
基金Supported by National Natural Science Foundation of China(Grant No.2018YFB1703000)State Key Laboratory of Metal Extrusion and Forging Equipment TechnologyChina National Heavy Machinery Research Institute Co.,Ltd.(Grant No.B2408100.W19)。
文摘The solenoid switching valve(SSV)is the key control component of heavy equipment such as continuous casting machines.However,the incompatibility of structural parameters increases the opening and closing time of the SSV.Therefore,this study proposes an optimized design method for an SSV to improve its dynamic performance.First,a multi-physics field-coupling model of the SSV is built,and the effects of different structural parameters on the electromagnetic characteristics are analyzed.After identifying the key influencing parameters,second-order response surface models are established to efficiently predict the opening and closing time.Subsequently,based on the nondominated sorting genetic algorithmⅡ(NSGA-Ⅱ),multi-objective optimization is applied to obtain the Pareto optimal solution of the structural parameters under the double-voltage driving strategy.The structure of the solenoid and valve as well as the dynamic characteristics of the valve are improved.Compared with those before optimization,the optimization results show that the opening and closing time of the optimized SSV are reduced by 24.38%and 51.8%,respectively,and the volume is reduced by 19.7%.The research results and the influence of the solenoid structural parameters on the electromagnetic force provide significant guidance for the design of this type of valve.
基金supported by the Chongqing Human Resources and Social Security Bureau(Grant No.CX2023079)the Fundamental Research Funds for the Central Universities,China(Grant Nos.2023CDJXY-049 and 2024CDJXY-022)the National Natural Science Foundation of China(Grant Nos.T2350007 and 127404)。
文摘Previous studies on droplet generation in microfluidics mainly focus on the monodisperse droplet,but limited attention has paid to the generation of droplet groups composed of multiple droplets with different volumes or components.In this study,a programmable electromagnetic valve is externally connected with the microfluidic chip featuring a conventional flow-focused structure.Different from the previous situation where only one droplet is generated by a single actuation of the electromagnetic valve,by precisely controlling the opening and closing of the valve,the continuous phase fluid exhibits periodic flow in the channel,and we realized the generation of a droplet group by a single actuation of the valve,and the number and volume of the droplets in each group can be regulated.Specifically,the number of large droplets in a droplet group is mainly determined by the opening time of the electromagnetic valve and the two-phase flow rate,and the number of small droplets is dominated by the valve closing time.The volume of individual droplets in a droplet group is largely dependent on the flow rate of the continuous phase.Our study extends the understanding of microfluidic droplet formation.It provides a feasible method for the efficient preparation of polydisperse droplets,which is important for microfluidic chip-based droplet control and has potential applications in industries related to microfluidic droplets.
基金Supported by National Natural Science Foundation of China(Grant No.51675124)
文摘Pneumatic muscles with similar characteristics to biological muscles have been widely used in robots, and thus are promising drivers for frog inspired robots. How- ever, the application and nonlinearity of the pneumatic system limit the advance. On the basis of the swimming mechanism of the frog, a frog-inspired robot based on pneumatic muscles is developed. To realize the indepen- dent tasks by the robot, a pneumatic system with internal chambers, micro air pump, and valves is implemented. The micro pump is used to maintain the pressure difference between the source and exhaust chambers. The pneumatic muscles are controlled by high-speed switch valves which can reduce the robot cost, volume, and mass. A dynamic model of the pneumatic system is established for the sim- ulation to estimate the system, including the chamber, muscle, and pneumatic circuit models. The robot design is verified by the robot swimming experiments and the dynamic model is verified through the experiments and simulations of the pneumatic system. The simulation results are compared to analyze the functions of the source pressure, internal volume of the muscle, and circuit flow rate which is proved the main factor that limits the response of muscle pressure. The proposed research provides the application of the pneumatic muscles in the frog inspired robot and the pneumatic model to study muscle controller.
文摘This paper reviews recent developments in digital switched hydraulics particularly the switched inertance hydraulic systems （SIHSs）. The performance of SIHSs is presented in brief with a discussion of several possible configurations and control strategies. The soft switching technology and high-speed switching valve design techniques are discussed. Challenges and recommendations are given based on the current research achievements.
